The invention relates to molding or replication tooling. In particular, the invention relates to laser machined mold or replication tooling useful for the ultimate production of structured articles, such as bristles of a liquid applicator.
Molding or replicating tooling has been produced by several different techniques. These techniques include, for instance, machining and chemical processing. Machining is accomplished by cutting with a stylus or microfilming into a substance, such as a mold surface.
Devices which accomplish such machining are either manually, mechanically or electronically controlled. These devices are capable of producing surfaces with optical grade precision, depending upon their quality. U.S. Pat. No. 4,938,563 to Nelson et al discloses the use of a diamond stylus for cutting into a flat metal surface of a master tool or mold. U.S. Pat. No. 4,959,265 to Wood et al. discloses the use of a microdrill to form the mold for a pressure-sensitive adhesive tape fastener backing. U.S. Pat. No. 5,077,870 to Melby et al relates to the use of a microdrill to form a metal mold used to produce mushroom-type hook strips for a mechanical fastener. These methods are considered slow for all but the simplest replications. In addition, replacement of the stylus and drill bits is expensive and adds to the cost of the machining. Another method for the production of microstructured tooling relates to the use of sharpened or shaped structures, such as pins or rods, being forced into a relatively soft medium, such as described in U.S. Pat. No. 3,235,438 to Wisotzky. This patent also illustrates the traditional, multi-step approach to the production of a microreplication molding or tooling. A primary negative mold is prepared by forcing the structures into the relatively soft medium. Intermediate positive master molds are made from the negative primary mold and are then joined together to form a large positive mold. A large negative mold is then produced from the large positive mold, which is then used to produce replicated articles. Preparation of the final negative mold requires significant time and cost.
Lasers have been used to machine some finished articles, such as filters, award plaques, rubber stamps, and stencils, but lasers have not been used to make molds or replication toolings. U.S. Pat. No. 5,792,411 to Morris et al calls for laser use to cut cavities is a substrate for producing tooling which can be used for microreplication purpose.
Such toolings has not been shown to be used to produce a true mold into which a thermoplastic resin is injected in order to produce an elongated handle having a bristle portion, the latter acts as a liquid carrier.
This invention relates to a method of manufacturing a microreplication master tooling suitable for manufacturing replicated articles by machining a substrate surface with a laser light source to produce a plurality of laser drilled indentations on surface extending from the substrate surface into the substrate itself.
The invention also relates to a method of manufacturing a microreplication master tooling suitable for manufacturing replicated articles by machining a unitary substrate surface to produce at least one geometric structure having side surfaces extending into the substrate, such that the substrate provides structural means for producing articles replicated from the master tooling. The substrate may comprise two mating surfaces forming a mold into which an injectable thermoplastic material may be charged.
The invention also relates to a method of manufacturing an article such as a bristle containing member from a microreplication master tooling by machining tooling mold surfaces with a laser light source to produce a geometric structure in the mold surfaces. The mold is closed and a heated thermoplastic material is then applied into the mold through an entrance orifice. The thermoplastic is permitted to solidify to produce a replicated article of the tooling which may be a tiny bristled liquid applicator, and the thereby produced applicator is removed from the tooling or mold.
The invention further relates to an article, which is a bristles applicator that is manufactured by the method.